732 HTSTOLOGIC TECHNIC 



INJECTION 



Injection is used either for the rapid dissemination of fixing fluids 

 through whole organs, embryos, etc., or for the demonstration of blood 

 or lymphatic vessels. For the former purpose mercuric chlorid is the 

 most useful fixative, since it may be immediately followed by the in- 

 jection of a hardening fluid, alcohol, by which the remaining mercury 

 is dissolved out of the tissue before overfixation occurs. For the latter 

 purpose a colored fluid, either aqueous or gelatinous, is forced into the 

 blood or lymphatic vessels. Berlin blue, carmin, vermilion, and lamp- 

 black are the coloring matters most frequently used. The last two 

 merely require suspension in a gelatinous or an aqueous menstruum; 

 the preparation of Berlin blue and carmin is somewhat more com- 

 plicated. 



Berlin Blue Gelatin Mass: 



Saturated aqueous solution (1 to 20) of 



Berlin blue (Griibler's) 100 c.c. 



Pure French gelatin (in sheets) 5 to 10 grm. 



The gelatin should be quickly washed to remove dust, etc., and then 

 placed for several hours in a very little distilled water until it becomes 

 swollen and soft. The superfluous water is then poured off, and the 

 gelatin melted over a water bath. The warmed solution of Berlin blue 

 may now be added, a little at a time, and continuously stirred. Finally, 

 the mixture is filtered through cotton flannel (or flannel) which has 

 been previously wrung out of hot water. If the mass is not to be used 

 at once, a few crystals of thymol may be added as a preservative, or, 

 after cooling, a little methylic alcohol may be floated upon the surface of 

 the solidified mass. It is better to use it at once. 

 Carmin Gelatin Mass: 



Carmin (Griibler's) 3 grm. 



Ammonium hydrate, strong 6 c.c. 



Pure French gelatin 7 grm. 



Distilled water 80 c.c. 



The gelatin is prepared and melted as above, 50 c.c. of the water being 

 used, and the evaporation replaced. The carmin is rubbed up in a 

 mortar with the remaining 30 c.c. of the water, and the ammonia is 

 added to render the carmin soluble. The mixture is now permitted to 



